U.S. patent application number 13/131401 was filed with the patent office on 2011-10-06 for cooling for hybrid electric vehicle.
This patent application is currently assigned to ETV ENERGY LTD.. Invention is credited to David Lior.
Application Number | 20110239659 13/131401 |
Document ID | / |
Family ID | 40637530 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239659 |
Kind Code |
A1 |
Lior; David |
October 6, 2011 |
COOLING FOR HYBRID ELECTRIC VEHICLE
Abstract
Hybrid gas-turbine electric vehicles and methods for operating
hybrid gas-turbine electric vehicles are provided that make use of
the gas-turbine for efficiently providing cooling for the
vehicle.
Inventors: |
Lior; David; (Herzliya,
IL) |
Assignee: |
ETV ENERGY LTD.
Herzliya
IL
|
Family ID: |
40637530 |
Appl. No.: |
13/131401 |
Filed: |
August 30, 2009 |
PCT Filed: |
August 30, 2009 |
PCT NO: |
PCT/IB09/53781 |
371 Date: |
June 22, 2011 |
Current U.S.
Class: |
60/783 ; 60/784;
903/906; 903/907 |
Current CPC
Class: |
F02C 7/105 20130101;
B60L 2240/445 20130101; F02C 6/08 20130101; Y02T 50/60 20130101;
B60L 2260/28 20130101; B60L 1/003 20130101; B60L 2210/40 20130101;
Y02T 10/70 20130101; B60H 1/004 20130101; F02C 6/20 20130101; B60L
50/61 20190201; B60L 58/26 20190201; B60L 2220/46 20130101; Y02T
10/7072 20130101; B60L 7/14 20130101; H01M 10/44 20130101; Y02T
10/62 20130101; Y02E 60/10 20130101; Y02T 10/72 20130101; B60L
50/40 20190201; B60L 2200/26 20130101 |
Class at
Publication: |
60/783 ; 60/784;
903/906; 903/907 |
International
Class: |
B60H 1/32 20060101
B60H001/32; F02C 6/20 20060101 F02C006/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2008 |
US |
61/122468 |
Mar 18, 2009 |
GB |
0904632.7 |
Claims
1. A gas-turbine hybrid electric vehicle, comprising: a) a
generator for generating electric power; and b) a gas-turbine,
including an air intake, a combustor, a compressor and a turbine,
functionally associated with said generator and configured to
operate in at least two states: i. an active state wherein said
gas-turbine powers said generator to generate electric power; and
ii. a passive state where said gas-turbine functions as an
air-cycle machine to provide cooling for the vehicle.
2. The vehicle of claim 1, wherein configuration of said
gas-turbine to operate in said active state and in said passive
state includes a valve.
3. The vehicle of claim 2, further comprising an air-cycle machine
intake valve and wherein: said air-cycle machine intake valve is
configured to direct exhaust from said combustor to said turbine in
said active state; and said air-cycle machine intake valve is
configured to direct air from said air intake to said turbine while
bypassing said combustor in said passive state.
4. The vehicle of claim 1, wherein said gas-turbine comprises a
primary heat-exchanger to recover heat from exhaust gas exiting
said compressor to preheat air entering said combustor in said
active state.
5. The vehicle of claim 4, further comprising an air-cycle machine
heat-exchanger, configured to cool a cooling fluid when said
gas-turbine operates as an air-cycle machine in said passive state,
and an air-cycle machine heat-exchanger diverter valve, wherein:
said air-cycle machine heat-exchanger diverter valve is configured
to direct gas exiting said turbine to pass through said primary
heat-exchanger in said active state; and said air-cycle machine
heat-exchanger diverter valve is configured to direct gas exiting
said turbine to bypass said primary heat-exchanger and to pass
through said air-cycle machine heat-exchanger in said passive
state.
6. The vehicle of claim 1, further comprising an air-cycle machine
motor, configured for driving said gas-turbine to operate as an
air-cycle machine in said passive state.
7. The vehicle of claim 1, wherein said generator is configured to
drive said gas-turbine to function as an air-cycle machine in said
passive state.
8. The vehicle of claim 1, further comprising at least one
rechargeable power storage unit for storing electric power
generated by said electric generator and for releasing stored power
as electric power to optionally power said gas-turbine in said
passive state.
9. The vehicle of claim 1, further comprising an absorption chiller
for providing cooling for the vehicle.
10. The vehicle of claim 9, wherein said absorption chiller is
configured to be driven by exhaust heat produced by said
gas-turbine.
11. The vehicle of claim 10, wherein said absorption chiller is
configured to be driven by exhaust heat produced by said
gas-turbine when operated in said active state.
12. The vehicle of claim 10, wherein said absorption chiller is
configured to be driven by exhaust heat produced by said
gas-turbine when operated as an air-cycle machine in said passive
state.
13. The vehicle of claim 10, further comprising a variable chiller
diverter valve, configured to regulate the amount of exhaust gas
exiting said compressor that is directed to drive said absorption
chiller.
14. The vehicle of claim 1, devoid of an electric-powered
air-conditioner for providing cooling for the vehicle.
15. The vehicle of claim 1, further comprising an electric-powered
air-conditioner for providing cooling for the vehicle.
16. The vehicle of claim 15, wherein said air-conditioner is
operable when said gas-turbine is in said active state.
17. The vehicle of claim 15, wherein said air-conditioner is
operable when said gas-turbine is in said inactive state.
18. A method of operating a hybrid gas-turbine electric vehicle,
comprising: a) in a first operation mode, providing electric power
to an electric drive motor of the vehicle with electric power
generated by an electric generator powered by a gas-turbine
operating in an active state; and b) switching to a second
operation mode, wherein said gas-turbine is in a passive state
operating as an air-cycle machine to provide cooling for the
vehicle.
19. The method of claim 18, in said first operation mode, directing
exhaust from said gas-turbine to drive an absorption chiller to
provide cooling for the vehicle.
20. The method of claim 18, in said second operation mode,
directing exhaust from said gas-turbine to drive an absorption
chiller to provide cooling for the vehicle.
21. The method of claim 18, further comprising, in said first
operation mode, operating an air-conditioner to provide cooling for
the vehicle.
22. The method of claim 18, further comprising, in said second
operation mode, operating an air-conditioner to provide cooling for
the vehicle.
23. The method of claim 18, wherein said cooling is used to cool a
passenger compartment of the vehicle.
24. The method of claim 18, wherein said cooling is used to cool a
non-passenger cargo compartment of the vehicle.
25. The method of claim 18, wherein said cooling is used to cool a
power storage unit of the vehicle.
Description
RELATED APPLICATIONS
[0001] The present application gains priority from U.S. Provisional
Patent Application No. 61/122,468 filed 15 Dec. 2008 and from UK
Patent Application No. 0904632.7 filed 18 Mar. 2009.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention, in some embodiments, relates to the
field of cooling and more particularly, but not exclusively, to
cooling in hybrid gas-turbine electric vehicles.
[0003] Wheeled motor vehicles are an inseparable part of a modern
industrial society, providing cheap, simple and efficient transport
of people and goods. Such societies would function with great
difficulty without automobiles, trucks and buses which allow for
efficient concentration and distribution of industrial, commercial
and residential loci.
[0004] The ubiquity of motor vehicles is in a large part a result
of the existence of the internal combustion engine (ICE), primarily
Otto-cycle and Diesel-cycle engines powered by cheap and readily
available fossil fuel. ICEs have a reasonable power to weight ratio
and provide a wide range of power on demand. However, ICEs are
relatively inefficient and continuously produce harmful emissions
even when idling.
[0005] As more vehicles are available, the effects of harmful
emissions produced by ICEs (especially in crowded urban areas)
increase, leading to a need to reduce the emissions produced by
motor vehicles. Additionally, the possible shortage and/or increase
in the price of fossil fuels lead to a parallel need to reduce
fossil fuel consumption by motor vehicles.
[0006] An alternative to ICE-powered vehicles is all-electric
vehicles. All-electric vehicles have one or more electric motors
powered with electric power stored in on-board battery packs.
Electric motors produce no harmful emissions during operation. The
battery packs are charged from the electric grid, while the vehicle
is parked, with electric power produced in a remote central
electric power plant. Efficient, cheap, renewable or less-polluting
central power plants may be used to produce the electric power at
the central power plant. All-electric vehicles have a limited
range, especially when driving at high speeds or with heavy loads.
Additionally, the limited number of charge/discharge cycles
available to any battery means that vehicle battery packs are
eventually spent and then must be replaced. As a result, the
lifetime cost of operating the vehicle may be prohibitive.
[0007] In order to overcome some of the disadvantages of
ICE-powered and of all-electric vehicles, hybrid vehicles have been
developed. Such vehicles include an ICE, one or more electric
motors, an electric generator and battery packs to store electric
power. Hybrid vehicles produce fewer emissions and are more
fuel-efficient than ICE-powered vehicles and are not limited in
range like all-electric vehicles. There are different types of
hybrid vehicles each having advantages and disadvantages.
[0008] In some hybrid vehicles, the ICE primarily drives the
vehicle while the electric motors are configured to provide extra
driving power when needed, allowing the ICE to be smaller than
otherwise. Some such hybrid vehicles are configured to optionally
drive only with the electric motors, for example from a complete
stop allowing the ICE to be turned off when not needed to reduce
emissions.
[0009] In such vehicles, the batteries for providing power to the
electric motors are typically charged with electric power generated
by the on-board generator driven by the ICE and/or electric power
from the power grid while parking.
[0010] In some hybrid vehicles the electric motors primarily drive
the vehicle while the ICE acts as an on-board charger to generate
electric power to store in the battery pack and/or to directly
power the electric motors. In such vehicles, the battery packs may
be optionally charged with electric power from the power grid while
parking.
[0011] Often, hybrid vehicles are provided with regenerative
braking units that brake the vehicle by converting kinetic energy
to electric power that is subsequently stored in the battery packs.
The battery pack acts as an energy-sink, storing otherwise wasted
energy to be used by the electrical motors to drive the vehicle
when extra power is needed and consequently to reduce the use of
fuel by the ICE and increase the range of the vehicle.
[0012] Increasingly, vehicular air-conditioning, especially
cooling, is an important accessory in every vehicle, both for
passenger comfort and for safety. Drivers in non-air-conditioned
vehicles are more tired and more aggressive than air-conditioned
counterparts, and are therefore prone to mistakes and errors of
judgment. However, an air conditioning system is the largest
auxiliary load on a vehicle, using an amount of power that
significantly affects vehicle performance. For example, in one
study it was shown that air-conditioning reduces the fuel-economy
of efficient ICE-powered vehicles by about 50% and the range of
all-electric vehicles by about 36% (Farrington R and Rugh J,
"Impact of Vehicle Air-Conditioning on Fuel Economy, Tailpipe
Emissions and Electric Vehicle Range" presented at the Earth
Technologies Forum, Oct. 31, 2000).
[0013] The fact that the air conditioning system uses a significant
amount of power means that a given vehicle must have a larger ICE
to power the air conditioning unit to retain a desired level of
performance. Similarly, this means that a given vehicle must have
larger and heavier battery packs to power an air-conditioning unit
to retain a desired level of performance.
[0014] An additional problem for air-conditioned electric vehicles
relates to battery lifetime. As noted above, a battery has a
limited number of charge/recharge cycles. When a significant amount
of battery power is used for air-conditioning, battery lifetime is
reduced, increasing vehicle operating costs.
[0015] It would be highly desirable to have an air-conditioned
motor vehicle devoid of at least some of the limitations of
air-conditioned motor vehicles known in the art.
SUMMARY OF THE INVENTION
[0016] Aspects of the invention relate to cooling in hybrid
gas-turbine electric vehicles that in some embodiments have
advantages over known methods and vehicles. Specifically some
embodiments of the invention relate to hybrid gas-turbine electric
vehicles where, when the gas-turbine is not in an active state
powering a generator, the gas-turbine is used as an air-cycle
machine. In some embodiments, the gas-turbine is also used to
provide heat for driving an absorption chiller.
[0017] According to an aspect of some embodiments of the invention
there is provided a method of operating a hybrid gas-turbine
vehicle comprising: a) in a first operation mode, providing
electric power to an electric drive motor of the vehicle (to drive
the vehicle) with electric power generated by an electric generator
powered by a gas-turbine operating in an active state; and b)
switching to a second operation mode, wherein the gas-turbine is in
a passive state operating as an air-cycle machine to provide
cooling for the vehicle. In some embodiments, the electric power to
drive the vehicle is provided to the electric drive motor from a
power storage unit. In some embodiments, the electric power to
operate the gas-turbine as an air-cycle machine is provided from a
power storage unit.
[0018] In some embodiments, in the first operation mode the method
further comprises directing exhaust from the gas-turbine to drive
an absorption chiller to provide cooling for the vehicle.
[0019] In some embodiments, in the second operation mode the method
further comprises directing exhaust from the gas-turbine to drive
an absorption chiller to provide cooling for the vehicle, in some
embodiments in addition to the cooling provided by the gas-turbine
operating as an air-cycle machine.
[0020] In some embodiments, in the first operation mode the method
further comprises operating an air-conditioner to provide cooling
for the vehicle
[0021] In some embodiments, in the second operation mode the method
further comprises operating an air-conditioner to provide cooling
for the vehicle
[0022] In some embodiments, the cooling provided by the gas-turbine
operating as an air-cycle machine, by the absorption chiller and/or
by the air conditioner is used to cool a passenger compartment of
the vehicle. In some embodiments, the cooling provided by the
gas-turbine operating as an air-cycle machine, by the absorption
chiller and/or by the air conditioner is used to cool a
non-passenger cargo compartment of the vehicle. In some
embodiments, the cooling provided by the gas-turbine operating as
an air-cycle machine, by the absorption chiller and/or by the air
conditioner is used to cool a power storage unit, for example a
battery pack, of the vehicle.
[0023] According to an aspect of some embodiments of the invention
there is also provided a gas-turbine hybrid electric vehicle,
comprising: [0024] a) an electrical generator for generating
electric power; and [0025] b) a gas-turbine, including an air
intake, a combustor, a compressor and a turbine, functionally
associated with the generator and configured to operate in at least
two states: [0026] i. an active state (where fuel is burned in the
combustor and the released energy converted to mechanical energy by
expansion through the turbine) wherein the gas-turbine powers the
generator to generate electric power; and [0027] ii. a passive
state where the gas-turbine functions as an air-cycle machine to
provide cooling for the vehicle.
[0028] In some embodiments, the gas-turbine is configured for
operation according to a Brayton cycle. In some embodiments, the
gas-turbine is configured for operation according to an inverse
Brayton cycle. In some embodiments, the gas-turbine is a
multipressure mode gas-turbine configured for operation according
to an inverse Brayton cycle and according to a Brayton cycle.
[0029] In some embodiments, the configuration of the gas-turbine to
operate in the active state or in the passive state includes a
valve.
[0030] In some embodiments, the gas-turbine further comprises an
air-cycle machine intake valve and wherein: [0031] the air-cycle
machine intake valve is configured to direct exhaust from the
combustor to the turbine in the active state; and [0032] the
air-cycle machine intake valve is configured to direct air from the
air intake to the turbine while bypassing the combustor in the
passive state.
[0033] In some embodiments, the gas-turbine comprises a primary
heat-exchanger to recover heat from exhaust gas exiting the
compressor to preheat air entering the combustor in the active
state
[0034] In some embodiments, the gas-turbine further comprises an
air-cycle machine heat-exchanger, configured to cool a cooling
fluid when the gas-turbine operates as an air-cycle machine in the
passive state and an air-cycle machine heat-exchanger diverter
valve, wherein: [0035] the air-cycle machine heat-exchanger
diverter valve is configured to direct gas exiting the turbine to
pass through the primary heat-exchanger in the active state; and
[0036] the air-cycle machine heat-exchanger diverter valve is
configured to direct gas exiting the turbine to bypass the primary
heat-exchanger and to pass through the air-cycle machine
heat-exchanger in the passive state, thereby allowing the cooling
of the cooling fluid.
[0037] In some embodiments, a gas-turbine further comprises an
air-cycle machine motor, configured for driving the gas-turbine to
operate as an air-cycle machine in the passive state.
[0038] In some embodiments, the generator is configured to drive
the gas-turbine to function as an air-cycle machine in the passive
state.
[0039] In some embodiments, the vehicle further comprises at least
one rechargeable power storage unit for storing electric power
generated by the electric generator and for releasing stored power
as electric power to optionally power the gas-turbine in the
passive state.
[0040] In some embodiments, the vehicle further comprises an
absorption chiller for providing cooling for the vehicle. In some
embodiments, the absorption chiller is configured to be driven by
exhaust heat produced by the gas-turbine. For example, in some
embodiments the vehicle comprises a valve that optionally directs
at least a portion of the exhaust of the gas-turbine to drive the
absorption chiller. In some embodiments, the absorption chiller is
configured to be driven by exhaust heat produced by the gas-turbine
when operated in the active state. In some embodiments, the
absorption chiller is configured to be driven by exhaust heat
produced by the gas-turbine when operated as an air-cycle machine
in the passive state. In some embodiments, the gas-turbine further
comprises a variable chiller diverter valve, configured to regulate
the amount of exhaust gas exiting the compressor that is directed
to drive the absorption chiller.
[0041] In some embodiments, a vehicle of the invention is devoid of
an electric-powered air-conditioner for providing cooling for the
vehicle.
[0042] In some embodiments, a vehicle of the invention comprises an
electric-powered air-conditioner for providing cooling for the
vehicle. In some embodiments, the air-conditioner is operable when
the gas-turbine is in the active state. In some embodiments, the
air-conditioner is operable when the gas-turbine is in the inactive
state.
[0043] In some embodiments, the vehicle is configured to direct the
cooling provided by the gas-turbine in the passive state to a power
storage unit of the vehicle. In some embodiments, the vehicle is
configured to direct the cooling provided by the gas-turbine in the
passive state to a passenger compartment of the vehicle. In some
embodiments, the vehicle is configured to direct the cooling
provided by the gas-turbine in the passive state to a non-passenger
cargo compartment of the vehicle.
[0044] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention pertains. In case
of conflict, the patent specification, including definitions, will
control.
[0045] As used herein, the terms "comprising", "including",
"having" and grammatical variants thereof are to be taken as
specifying the stated features, integers, steps or components but
do not preclude the addition of one or more additional features,
integers, steps, components or groups thereof. These terms
encompass the terms "consisting of" and "consisting essentially
of".
[0046] The phrase "consisting essentially of" or grammatical
variants thereof when used herein are to be taken as specifying the
stated features, integers, steps or components but do not preclude
the addition of one or more additional features, integers, steps,
components or groups thereof but only if the additional features,
integers, steps, components or groups thereof do not materially
alter the basic and novel characteristics of the described
composition, device or method.
[0047] As used herein, the indefinite articles "a" and "an" mean
"at least one" or "one or more" unless the context clearly dictates
otherwise.
BRIEF DESCRIPTION OF THE FIGURES
[0048] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying figures.
The description, together with the figures, makes apparent how
embodiments of the invention may be practiced to a person having
ordinary skill in the art. The figures are for the purpose of
illustrative discussion of embodiments of the invention and no
attempt is made to show structural details of an embodiment in more
detail than is necessary for a fundamental understanding of the
invention. For the sake of clarity, some objects depicted in the
figures are not to scale.
[0049] In the Figures:
[0050] FIGS. 1A-1D are schematic depictions of an embodiment of a
vehicle including an inverse Brayton cycle gas-turbine operating
operable as an air-cycle machine; and
[0051] FIGS. 2A-2B are schematic depictions of an embodiment of a
vehicle including a Brayton cycle gas-turbine operating operable as
an air-cycle machine.
DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION
[0052] Aspects of the invention relate to cooling in hybrid
gas-turbine electric vehicles. Aspects of the invention relate to
hybrid gas-turbine electric vehicles including a cooling system
that in some embodiments comprises an absorption chiller. Aspects
of the invention relate to hybrid gas-turbine electric vehicles
including a cooling system that in some embodiments comprises an
air-cycle machine. In some embodiments, a gas-turbine of a hybrid
gas-turbine electric vehicle is used as an air-cycle machine to
provide cooling when the gas-turbine is not active for powering an
electric generator. In some embodiments, exhaust heat produced by
the gas-turbine operating as an air-cycle machine is used to drive
an absorption chiller.
[0053] The principles, uses and implementations of the teachings of
the invention may be better understood with reference to the
accompanying description and figures. Upon perusal of the
description and figures present herein, one skilled in the art is
able to implement the teachings of the invention without undue
effort or experimentation. In the figures, like reference numerals
refer to like parts throughout.
[0054] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details set forth herein. The invention
can be implemented with other embodiments and can be practiced or
carried out in various ways. It is also understood that the
phraseology and terminology employed herein is for descriptive
purpose and should not be regarded as limiting.
[0055] Gas-turbines are known for being lightweight, efficient,
reliable and requiring little maintenance. However, gas-turbines
are not well known for use with ground vehicles such as cars and
trucks for a number of reasons.
[0056] A first reason is that a given gas-turbine is designed to
generate a specific power output at highest efficiency. Generation
of power output that is greater or lesser than the designed power
output is significantly less efficient. Vehicles have highly
variable power demands, requiring more power for rapid acceleration
or climbing hills, requiring less power when cruising and virtually
no power when stopped.
[0057] A second reason is that the power requirements for ground
vehicles are low compared to the power gas-turbines efficiently
produce. Although large gas-turbines are relatively efficient, the
efficiency of a gas-turbine dramatically decreases with smaller
size (e.g., less than 300 kW) for various reasons including leakage
of heated gas from the combustor around the periphery of the
turbine, leakage which is more significant with smaller turbine
size.
[0058] A third reason is "turbine lag": it takes a noticeably long
time for a given gas-turbine to speed-up and stabilize to produce
more power, e.g., for acceleration.
[0059] A fourth reason is that the lifetime of gas-turbines is
severely limited by startup/shutdown events. Unlike an ICE, it is
not practical to shut down a gas-turbine when idling.
[0060] Capstone Turbine Corporation (Chatsworth, Calif., USA) has
proposed a hybrid gas-turbine electric bus, described in the
introduction of U.S. Pat. No. 6,526,757. Such a bus includes an
electric drive motor, a relatively small and light battery pack
which supplies power to the drive motor and a gas-turbine
functionally associated with a generator. The gas-turbine is the
primary source of power for the bus and is configured to power the
drive motor, to power auxiliary loads and to charge the battery
pack. The gas-turbine is selected having a designed power output
that is the average power required by the bus. During operation,
the gas-turbine is continuously operated at the designed power
output to having greatest efficiency. When the bus is stopped, the
electric power produced by the gas-turbine is used to charge the
battery pack and power the auxiliary loads. The battery pack
supplies additional electric power when the bus requires a greater
amount of power, for example for acceleration. A disadvantage of
such a method of operation is that the gas-turbine continuously
operates, producing harmful emissions.
[0061] It would be advantageous to operate a hybrid gas-turbine
electric vehicle where at least part of the time the gas-turbine is
in an active state operating as close as possible to the designed
power output, combusting fuel to power an electric generator and at
least part of the time the gas-turbine is in a passive state and
not combusting fuel to reduce emissions, where electric power for
operating the vehicle is drawn from a power storage unit such as a
battery pack. However, a major challenge in operating the vehicle
is cooling. As discussed in the introduction, air conditioning
requires a significant amount of power that severely reduces
vehicle performance.
[0062] When the gas-turbine of a gas-turbine electric hybrid
vehicle is in an active state, the gas-turbine can be configured to
be sufficiently powerful to produce enough electric power for
operating an air-conditioning unit. A disadvantage of such a
configuration is that the gas-turbine must produce more power to
power the air-conditioner and therefore produces more emissions,
and produces excess power when the air-conditioning unit is not
activated. Further, when the gas-turbine is in a passive state and
not an active state, the power to power the air-conditioner is
drawn from a power storage unit severely reduces vehicle
performance.
[0063] An aspect of some embodiments of the invention relates to
hybrid gas-turbine electric vehicles and methods of operating
hybrid gas-turbine electric vehicles that overcome some of the
problems associated with cooling as discussed above.
[0064] Some embodiments of the invention relate to an entirely
different concept of operation of a hybrid gas-turbine electric
vehicle at least two modes.
[0065] In the first mode, the gas-turbine of the vehicle is in an
active state (fuel is combusted in the combustor) and powers a
generator to provide electric power for the vehicle, for example
the drive motors and auxiliary loads. Extra power may be stored in
chargeable power storage unit such as a battery pack. In some
embodiments, cooling is provided by an absorption chiller driven by
otherwise wasted heat from gas-turbine exhaust.
[0066] In the second mode, the gas-turbine is in a passive state
(no fuel is combusted in the combustor) and electric power for the
vehicle is provided, for example, by the power storage unit. Such a
second mode allows emission-free operation of the vehicle, useful,
for example, for operation in urban areas. In some embodiments, use
of such a mode allows the vehicle to utilize cheap and relatively
environmentally friendly grid electric power. In some embodiments,
use of such a mode allows the vehicle to utilize cheap kinetic
energy recovered with the use of a regenerative braking system.
[0067] In some embodiments, in the second mode, cooling is provided
by using the gas-turbine as an air-cycle machine. As discussed
below, in some embodiments the coefficient of performance of the
gas-turbine operating as an air-cycle machine is approximately
1.
[0068] In some such embodiments, the hot exhaust generated by the
air-cycle machine is used to drive an absorption chiller to provide
additional cooling capacity. As discussed below, in embodiments the
coefficient of performance of a cooling unit using a gas-turbine as
an air-cycle machine together with an absorption chiller is at
least 3.
[0069] In some embodiments, the use of a passive gas-turbine as an
air-cycle machine allows implementation of efficient vehicular
cooling having one or more advantages.
[0070] Generally, a gas-turbine in the active state generates more
than enough waste heat to drive an absorption chiller but also
generates more than enough electric power to power an air
conditioner. However, an air conditioner uses electric power that
is otherwise available to power the drive motors, for example for
sudden acceleration or for high speed cruising. Thus in some
embodiments the teachings of the invention improve the performance
of a hybrid gas-turbine electric vehicle.
[0071] In some embodiments, the use of the gas-turbine as an
air-cycle machine, especially together with an absorption chiller
provides a practical source of cooling as an alternative to a
standard air conditioner.
[0072] In some embodiments, use of an absorption chiller instead of
an air conditioner provides a more robust, simpler to maintain
and/or more silent cooling system.
[0073] In some embodiments, use of waste heat for generating
cooling reduces the power requirements for cooling, giving the
vehicle improved performance, for example increased range from the
power storage unit and greater instantaneous performance.
[0074] In some embodiments, greater fuel efficiency is achieved. In
some embodiments, greater vehicular range is achieved.
Method of Operating a Hybrid Gas-Turbine Electric Vehicle
[0075] According to an aspect of some embodiments of the invention
there is provided a method of operating a hybrid gas-turbine
vehicle comprising: a) in a first operation mode, providing
electric power to an electric drive motor of the vehicle to drive
the vehicle with electric power generated by an electric generator
powered by a gas-turbine operating in an active state; and b)
switching to a second operation mode, wherein the gas-turbine is in
a passive state operating as an air-cycle machine to provide
cooling for the vehicle. In some embodiments, electric power to
drive the vehicle is provided to the electric motor from a power
storage unit. In some embodiments, electric power to power the
gas-turbine as an air-cycle machine is provided from a power
storage unit.
[0076] Any suitable gas-turbine may be used in implementing the
teachings of the invention, including Brayton cycle, inverse
Brayton cycle and multi-pressure gas-turbines such as described in
U.S. Pat. No. 6,526,757 or in copending provisional patent
application U.S. 61/116,394 of the Inventor.
[0077] In some embodiments, in the first operation mode, the method
further comprises directing exhaust from the gas-turbine to drive
an absorption chiller to provide cooling for the vehicle.
[0078] In some embodiments, in the second operation mode the method
further comprises directing exhaust from the gas-turbine to drive
an absorption chiller to provide cooling for the vehicle, in some
embodiments in addition to the cooling provided by the gas-turbine
operating as an air-cycle machine.
[0079] In some embodiments, in the first operation mode the method
further comprises operating an air-conditioner to provide cooling
for the vehicle
[0080] In some embodiments, in the second operation mode the method
further comprises operating an air-conditioner to provide cooling
for the vehicle
[0081] In some embodiments, the cooling provided by the gas-turbine
operating as an air-cycle machine, by the absorption chiller and/or
by the air conditioner is used to cool a passenger compartment of
the vehicle. In some embodiments, the cooling provided by the
gas-turbine operating as an air-cycle machine, by the absorption
chiller and/or by the air conditioner is used to cool a
non-passenger cargo compartment of the vehicle.
[0082] Although the method of operating a hybrid gas-turbine
electric vehicle described herein may be implemented using any
suitable hybrid gas-turbine electric vehicle, in some embodiments
it is preferred to implement the method using a hybrid gas-turbine
electric vehicle of the invention.
Hybrid Gas-Turbine Electric Vehicle
[0083] According to an aspect of some embodiments of the invention
there is provided a hybrid gas-turbine electric vehicle.
[0084] According to an aspect of some embodiments of the invention
there is provided a gas-turbine hybrid electric vehicle,
comprising: [0085] a) an electrical generator (a machine that
converts mechanical energy to electrical energy) for generating
electric power; and [0086] b) a gas-turbine, including an air
intake, a combustor, a compressor and a turbine, functionally
associated with the generator and configured to operate in at least
two states: [0087] i. an active state, where fuel is burned in the
combustor and the released energy converted to mechanical energy by
expansion through the turbine, wherein the gas-turbine powers the
generator to generate electric power; and [0088] ii. a passive
state where the gas-turbine functions as an air-cycle machine to
provide cooling for the vehicle.
[0089] Generally, a vehicle of the invention is any suitable type
of vehicle. A vehicle of the invention is preferably a
wheeled-vehicle such as an automobile, a minibus (having a capacity
of up to ten seated passengers and a driver), a bus, a light truck
(up to about 3500 kilogram gross vehicular mass, including pickups,
SUVs, vans and minivans) or a heavy truck (from about 3500 kilogram
gross vehicular mass). That said, in some embodiments, a vehicle of
the invention is a track-riding vehicle (e.g., a train or tram) or
a track-laying vehicle.
[0090] The gas-turbine may be any suitable gas-turbine. In some
embodiments, the gas-turbine is configured for operation according
to a Brayton cycle. In some embodiments, the gas-turbine is
configured for operation according to an inverse Brayton cycle. In
some embodiments, the gas-turbine is a multipressure mode
gas-turbine configured for operation according to an inverse
Brayton cycle and according to a Brayton cycle, for example as
described in U.S. Pat. No. 6,526,757 or in copending provisional
patent application U.S. 61/116,394 of the Inventor.
[0091] In some embodiments, the configuration of the gas-turbine to
operate in the active state or in the passive state includes a
valve.
[0092] In some embodiments, the gas-turbine further comprises an
air-cycle machine intake valve and wherein: the air-cycle machine
intake valve is configured to direct exhaust from the combustor to
the turbine in the active state; and the air-cycle machine valve is
configured to direct air from the air intake to the turbine while
bypassing the combustor in the passive state. An air-cycle machine
intake valve may be physically implemented using any suitable valve
or combination of valves. In some embodiments, the air-cycle
machine intake valve is implemented with one or more valve members
held in one more valve bodies.
[0093] In some embodiments, the gas-turbine comprises a primary
heat-exchanger to recover heat from exhaust gas exiting the
compressor to preheat air entering the combustor in the active
state. In such embodiments, any suitable type of primary
heat-exchanger may be used including a recuperator or a
regenerator, especially a rotary regenerator.
[0094] In some embodiments, the gas-turbine further comprises an
air-cycle machine heat-exchanger, configured to cool a cooling
fluid when the gas-turbine operates as an air-cycle machine and an
air-cycle machine heat-exchanger diverter valve, wherein: the
air-cycle machine heat-exchanger diverter valve is configured to
direct gas exiting the turbine to pass through the primary
heat-exchanger in the active state; and the air-cycle machine
heat-exchanger diverter valve is configured to direct gas exiting
the turbine to bypass the primary heat-exchanger and to pass
through the air-cycle machine heat-exchanger, thereby allowing the
cooling of the cooling fluid in the passive state. An air-cycle
machine heat-exchanger diverter valve may be physically implemented
using any suitable valve or combination of valves. In some
embodiments, the air-cycle machine intake valve is implemented with
one or more valve members held in one more valve bodies.
[0095] In some embodiments, a gas-turbine further comprises an
air-cycle machine motor, configured for driving the gas-turbine to
operate as an air-cycle machine in the passive state.
[0096] In some embodiments, the generator is configured to drive
the gas-turbine to function as an air-cycle machine in the passive
state.
Power Storage Unit
[0097] In some embodiments, the vehicle further comprises at least
one rechargeable power storage unit for storing electric power
generated by the electric generator and for releasing stored power
as electric power to optionally power the gas-turbine in the
passive state. Any suitable rechargeable power storage unit may be
used, for example power storage assemblies known in the art of
all-electric and hybrid ICE electric vehicles, for example a
battery pack, a capacitor or a gyroscopic energy storing system. In
some embodiments, a power storage unit comprises a battery pack. In
such embodiments, electric power received from the power-management
unit is stored as chemical energy and is released, when required as
electrical power. Any suitable battery chemistry may be used, for
example lead-acid, nickel cadmium, nickel metal hydride, lithium
ion, lithium ion polymer, zinc air and molten salt chemistry. In
some embodiments, a power storage unit comprises a capacitor, for
example an ultracapacitor such as is available from Maxwell
Technologies (San Diego, Calif., USA) or as described in U.S. Pat.
No. 6,787,235 or U.S. Pat. No. 6,602,742. In some embodiments, a
power storage unit comprises both a capacitor and a battery
pack.
Absorption Chiller
[0098] In some embodiments, the vehicle further comprises an
absorption chiller for providing cooling for the vehicle. An
absorption chiller is a well-known device that utilizes a heat
source to provide cooling. In such embodiments, any suitable
absorption chiller is used including NH.sub.3/H.sub.2O,
NH.sub.3/H.sub.2/H.sub.2O, LiBr/H.sub.2O, H.sub.2O/H.sub.2SO.sub.4
and air/water/salt absorption chillers. Absorption chillers are
commercially available, for example, from Dometic Corporation 2008
(Elkhart, Ind., USA).
[0099] In some embodiments, the absorption chiller is configured to
be driven by exhaust heat produced by the gas-turbine, for example
by providing a valve that optionally directs at least a portion of
the exhaust of the gas-turbine to drive the absorption chiller.
Exhaust waste heat that would otherwise be released to the
atmosphere is captured and used. In some embodiments, the
absorption chiller is configured to be driven by exhaust heat
produced by the gas-turbine when operated in the active state. In
some embodiments, the absorption chiller is configured to be driven
by exhaust heat produced by the gas-turbine when operated as an
air-cycle machine in the passive state.
[0100] In some embodiments, the gas-turbine further comprises a
variable chiller diverter valve, configured to regulate the amount
of exhaust gas exiting the compressor that is directed to drive the
absorption chiller. A variable chiller diverter valve may be
physically implemented using any suitable valve or combination of
valves. In some embodiments, the variable chiller diverter valve is
implemented with one or more valve members held in one more valve
bodies.
[0101] In some embodiments, a vehicle of the invention is devoid of
an electric-powered air-conditioner for providing cooling for the
vehicle.
[0102] In some embodiments, a vehicle of the invention comprises an
electric-powered air-conditioner for providing cooling for the
vehicle. In some embodiments, the air-conditioner is operable when
the gas-turbine is in the active state. In some embodiments, the
air-conditioner is operable when the gas-turbine is in the inactive
state.
Electric Drive Motors
[0103] In some embodiments, a vehicle of the invention is provided
with at least one electric drive motor to provide the motive force
to move the vehicle, similarly to all-electric or hybrid ICE
electric vehicles known in the art.
[0104] In some embodiments, a vehicle of the invention has a single
drive motor functionally associated with one or more wheel axes. In
some embodiments, a vehicle of the invention has two drive motors,
in some embodiments each functionally associated with a different
drive wheel or a different wheel axis. In some embodiments, a
vehicle of the invention has more than two drive motors, e.g.
three, four or more drive motors.
[0105] Similarly to some all-electric or hybrid ICE electric
vehicles known in the art, the drive motor or motors of some
embodiments of a vehicle of the invention are DC motors, for
example, serial-wound DC motors.
[0106] Similarly to some all-electric or hybrid ICE electric
vehicles known in the art, the drive motor or motors of some
embodiments of a vehicle of the invention are AC motors, for
example, induction motors or permanent magnet AC motors.
Regenerative Braking Unit
[0107] Some embodiments of a vehicle of the invention also comprise
a regenerative braking unit, configured for converting kinetic
energy of the vehicle to electrical power. In some embodiments, the
electrical power is used to charge the power storage unit and/or to
power the at least one driving motors and/or to power an auxiliary
load.
Grid Charging Unit
[0108] Some embodiments of a vehicle of the invention also comprise
a grid charging unit configured to accept electrical power from an
external source (e.g., an electrical power grid, a dedicated
vehicle recharging station) to charge the power storage unit. Grid
charging assemblies are well-known in the art of all-electric
vehicles. In some embodiments, a grid charging unit is configured
for conductive coupling to an external power source. In some
embodiments, a grid charging unit is configured for inductive
coupling to an external power source.
Power-Management Unit
[0109] Some embodiments of a vehicle of the invention include a
power-management unit. In general terms, a power-management unit
accepts electrical power from power-supplying components of the
vehicle and distributes the power to power-using components, as
required. In some embodiments, a power distribution is configured
to change the characteristics of a current received from a
power-supplying component to characteristics of a current required
from a power-using component. Characteristics that are typically
changed include AC to DC conversion, DC to AC conversion, phase of
AC current, frequency of AC current and voltage. A typical
power-management unit includes control circuitry, power
transmission circuitry, switches, transformers, rectifiers,
inverters and control processors. A power-management unit useful
for implementing the teachings of the invention is similar to
power-management units used in hybrid ICE electric vehicles or
known hybrid gas-turbine electric vehicles.
[0110] In some embodiments, the main power-using components of a
vehicle of the invention are the drive motor or motors. In some
embodiments at least one drive motor is a DC motor and the power
management unit is configured to provide DC current to the drive
motor. In some embodiments at least one drive motor is an AC motor
and the power management unit is configured to provide AC current
to the drive motor. The amount of power required by the at least
one drive motor and provided by the power-management unit is
determined primarily by the vehicle operator (driver) and may range
from no power when the vehicle is stopped to maximal power for
high-speed driving, for climbing hills or transporting heavy cargo.
In some embodiments, the amount of power required is communicated
to the power-management unit by the vehicle operator using an
operator-vehicle interface.
[0111] Additional power using-components are the auxiliary loads,
especially cooling. The amount of power required by the auxiliary
loads, excluding cooling, is relatively minor and constant. The
amount of power required by cooling is primarily determined by the
operator's preference, the weather and the exact implementation of
the invention. Generally, an air conditioner unit, if present and
operated, requires a significant amount of power. Generally, power
is required to operate the gas-turbine in a passive state as an
air-cycle machine. Generally, insignificant or substantially no
power is required by an absorption cooler driven by the exhaust of
the gas-turbine, whether in the active state or in the passive
state. In some embodiments some components of the auxiliary load
require DC current and the power management unit is configured to
provide DC current to such components. In some embodiments some
components of the auxiliary load require AC current and the power
management unit is configured to provide AC current to such
components.
[0112] An important power-supplying component is the electric
generator when the gas-turbine is in an active state. In some
embodiments, a generator generates DC current and the power
management unit is configured to accept DC current from the
generator. In some embodiments, a generator generates AC current
and the power management unit is configured to accept AC current
from the generator.
[0113] The power storage unit is both a power-using component and a
power-supplying component. In some embodiments, the
power-management unit is configured to control the amount of
electrical power drawn from the power storage unit, for example to
power the at least one drive motor or the auxiliary loads.
Generally, the power drawn from a power storage unit is DC current
and the power management unit is configured to accept the DC
current from the power storage unit. In some embodiments, the
power-management unit is configured to control the amount of
electric power sent to the power storage unit for storage.
Generally, a power storage unit accepts DC current for storage and
the power management unit is configured to send DC current to the
power storage unit for storage.
[0114] Embodiments of the method of the invention are described
hereinbelow with reference to an embodiment of a vehicle of the
invention, vehicle 10, schematically depicted in FIGS. 1A, 1B, 1C
and 1D.
[0115] Vehicle 10, schematically depicted in FIG. 1A, comprises a
power-management unit 12, a gas-turbine 14, an electric generator
16 (e.g., an alternator), a power storage unit 18, four electric
drive motors 20, an air-cycle machine heat-exchanger 22, an
absorption chiller 24, an air conditioner 26, a grid-charging unit
28 and four regenerative braking units 30.
[0116] Gas-turbine 14, schematically depicted in FIGS. 1B, 1C and
1D, is a single-spool gas-turbine configured to operate according
to an inverse Brayton cycle and includes an air intake 32 (depicted
twice in FIG. 1B due to schematic depiction), a rotary regenerator
34, a combustor 36, a turbine 38, a compressor 40, a shaft 42, an
exhaust duct 44, a variable chiller diverter valve 46, and an
air-cycle machine heat-exchanger diverter valve 50. The various
components of gas-turbine 14 are standard components known in the
art of microturbines such as commercially available from Capstone
Turbine Corporation (Chatsworth, Calif., USA) and described, for
example, in "Guide to Microturbines" by Bernard F. Kolanowski,
published by The Fairmont Press, Inc., 2004 (ISBN 0881734187,
9780881734188)
[0117] Generator 16 is a standard high-speed alternator suitable
for use with a vehicular microturbine. Shaft 42 is the rotor of
generator 16 so that generator 16 is driven directly by gas-turbine
14. Generator 16 is also configured to function in reverse as a
motor, applying a force that rotates shaft 42 and consequently
compressor 40 and turbine 38.
[0118] Rotary regenerator 34 is a primary heat-exchanger for
gas-turbine 14, configured to recover heat from exhaust gas exiting
compressor 40 to preheat air entering combustor 36 to increase the
thermal efficiency of gas-turbine 14.
[0119] Air-cycle machine heat-exchanger 22 is a standard
heat-exchanger including two separate conduits: a gas conduit 22a
and a cooling fluid conduit 22b. Gas conduit 22a provides fluid
communication for gas from turbine 38 through a gas conduit inlet
52, air-cycle machine heat-exchanger 22, a gas conduit outlet 54 to
compressor 40. Cooling fluid conduit 22b includes fluid conduit
inlet 56, air-cycle machine heat-exchanger 22, fluid conduit outlet
58, pump 60 and passenger compartment cooling element 62. Air-cycle
machine heat-exchanger 22 is configured so that gas entering gas
conduit inlet 52 and exiting gas conduit outlet 54 accepts heat
from fluid in cooling fluid conduit 22b.
[0120] Variable chiller diverter valve 46 is a continuously
variable valve configured to regulate the amount of exhaust gas
exiting from compressor 40 that is directed to enter absorption
chiller 24, with excess exhaust gas directed directly to exhaust
duct 44.
[0121] Absorption chiller 24 is a standard absorption chiller,
configured to provide cooling for vehicle 10, especially for the
passenger compartment of vehicle 10. Absorption chiller 24 is
driven by heat from exhaust gas exiting compressor 40 and directed
to absorption chiller 24 by variable chiller diverter valve 46.
[0122] Air-cycle machine intake valve 48 is a two-state valve
configured to direct gas into turbine 38 either to define fluid
communication between air intake 32 and turbine 38 through
combustor 36, thereby directing exhaust gas exiting combustor 36
into turbine 38 or to define fluid communication between air intake
32 and turbine 38 bypassing combustor 36, thereby directing ambient
air from air intake 32 into turbine 38, bypassing combustor 36 and
also rotary regenerator 34.
[0123] Air-cycle machine heat-exchanger diverter valve 50 is a
two-state valve configured to direct gas exiting from turbine 38,
either to enter rotary regenerator 34 or to bypass rotary
regenerator 34 and to enter air-cycle machine heat-exchanger 22
through gas conduit inlet 52.
[0124] Air conditioner 26 is a standard vehicular gas-evaporation
air conditioner.
Inverse Brayton Gas-Turbine in Active State for Generating Electric
Power (FIG. 1B)
[0125] Under certain driving conditions, for example in some
embodiments during high-speed cruising, gas-turbine 14 is operated
in an active state, burning fuel in combustor 36 to release energy
that is converted to mechanical energy by expansion through turbine
38, as depicted in FIG. 1B.
[0126] Air-cycle machine intake valve 48 is set to direct exhaust
gas exiting combustor 36 into turbine 38.
[0127] Air-cycle machine heat-exchanger diverter valve 50 is set to
direct exhaust gas exiting turbine 38 to pass through the hot
stream section of rotary regenerator 34.
[0128] Ambient air enters air intake 32, passes through the cold
stream section of rotary regenerator 34 to be heated before
entering combustor 36. In combustor 36, the heated air is mixed
with fuel and the mixture combusted. The hot exhaust gas resulting
from the combustion is directed by air-cycle machine intake valve
48 into turbine 38. The hot exhaust gas expands through and rotates
turbine 38 (consequently rotating shaft 42 and compressor 40),
passes through air-cycle machine heat-exchanger diverter valve 50,
through the hot stream section of rotary regenerator 34. The hot
exhaust gas is then forced by compressor 40 (driven by shaft 42)
into exhaust duct 44 to be ejected to the atmosphere through
exhaust duct 44.
[0129] One end of shaft 42 constitutes the rotor of generator 16.
As a result, rotation of shaft 42 by exhaust gases expanding
through turbine 38 causes generator 16 to generate electric
power.
[0130] The electric power generated by generator 16 is directed to
power-management unit 12 which directs the electric power to power
drive motors 20 in accordance with the instructions of the vehicle
driver and to power auxiliary loads. Excess electric power is
directed to charge power storage unit 18. If drive motor 20
requires more power than is generated by generator 16, for example
during hill-climbing, power-management unit 12 draws the required
electric power from power storage unit 18.
[0131] When applicable, for example during braking or downhill
driving, electric power generated by regenerative braking unit 30
is directed to power-management unit 12 to power drive motor 20, to
power auxiliary loads and/or to charge power storage unit 18.
Air Conditioner
[0132] In some embodiments, cooling is performed in the usual way:
power-management unit 12 supplies electric power to air conditioner
26 which functions in the usual way, cooling air, for example, for
cooling the passenger compartment. However, as air conditioner 26
requires a significant amount of power, in some embodiments vehicle
performance is adversely affected, for example when accelerating
for passing, when climbing hills or when transporting heavy cargo.
That said, in some embodiments, gas-turbine 14 together with
generator 16 has sufficient electric power-generating capacity so
that the amount of electric power required to operate air
conditioner 26 has no substantial effect on the performance of
vehicle 10.
Absorption Chiller (FIG. 1C)
[0133] In some embodiments, instead of or in addition to using air
conditioner 26, variable chiller diverter valve 46 is set to direct
hot exhaust gas exiting compressor 40 to drive absorption chiller
24, see FIG. 1C. Specifically, variable chiller diverter valve 46
diverts and regulates the amount of hot exhaust gas exiting
compressor 40 entering absorption chiller 24 required to produce a
desired degree of cooling. Absorption chiller 24 then functions in
the usual way, for example, for cooling the passenger compartment
of vehicle 10.
Inverse Brayton Gas-Turbine as Air-Cycle Machine (FIG. 1D)
[0134] Under certain driving conditions, for example in some
embodiments during urban driving, in stop-and-go driving in a
traffic jam, gas-turbine 14 is operated in a passive state where
fuel is not combusted in combustor 36. When gas-turbine 14 is in a
passive state, electric power for powering drive motors 20 or
auxiliary loads is supplied by power-management unit 12, the
electric power drawn from power storage unit 18 or generated by
regenerative braking unit 30. When gas-turbine 14 is in a passive
state, gas-turbine 14 optionally functions as an air-cycle machine
to provide cooling for vehicle 10, as detailed below.
Air Conditioner
[0135] In some embodiments, cooling is performed in the usual way:
power-management unit 12 supplies electric power to air conditioner
26 which functions in the usual way, cooling air, for example, for
cooling the passenger compartment. It is important to note that
generally this is undesirable because, as discussed in the
introduction, an air conditioning unit such as 26 requires an
amount of power that severely limits vehicle performance.
Air-Cycle Machine (FIG. 1D)
[0136] In some embodiments, instead of or in addition to using air
conditioner 26, gas-turbine 14 is used as an air-cycle machine to
produce cool air, FIG. 1D. Air-cycle machines are known in the art
of cooling passenger aircraft.
[0137] Pump 60 of air-cycle machine heat-exchanger 22 is activated,
cycling fluid into fluid conduit inlet 56, through cooling fluid
conduit 22b of air-cycle machine heat-exchanger 22, out through
fluid conduit outlet 58, into passenger compartment cooling element
62 and back into pump 60.
[0138] Air-cycle machine intake valve 48 is set to direct air
entering air intake 32 is into turbine 38 and to bypass combustor
36 and rotary regenerator 34.
[0139] Air-cycle machine heat-exchanger diverter valve 50 is set to
direct exhaust gas exiting turbine 38 to enter air-cycle machine
heat-exchanger 22 and to bypass rotary regenerator 34.
[0140] Generator 16 is set to function as a motor using power
supplied by power-management unit 12 from power storage unit 18
and/or regenerative braking unit 30 to rotate turbine 38 and
compressor 40 through shaft 42.
[0141] Compressor 40 draws air from the ducts leading to air-cycle
machine heat-exchanger 22, from gas conduit 22a of air-cycle
machine heat-exchanger 22, and from the ducts leading to turbine
38, generating low pressure in air-cycle machine heat-exchanger 22
and in the ducts leading to turbine 38. Ambient air enters air
intake 32, passes through air-cycle machine intake valve 48 and is
drawn through turbine 38. When exiting turbine 38, the air expands
and cools. The cool air passes through air-cycle machine
heat-exchanger diverter valve 50 to enter gas conduit 22a of
air-cycle machine heat-exchanger 22 through gas conduit inlet 52,
absorbs heat from cooling fluid in cooling fluid conduit 22b and
exits through gas conduit outlet 54 to be drawn into compressor
40.
[0142] Cooling fluid in passenger compartment cooling element 62
absorbs heat from the passenger compartment of vehicle 10,
transfers the heat to the air in gas conduit 22a of air-cycle
machine heat-exchanger 22 and is therefore cooled.
[0143] The air draw into compressor 40 is compressed using the
turbine expansion energy to supplement the motor power output and
consequently heated, passes through variable chiller diverter valve
46 and expelled through exhaust duct 44.
Absorption Chiller
[0144] In some embodiments, for example when greater cooling
capacity is required or in order to reduce the amount of power
required by generator 16 to drive gas-turbine 14 as an air-cycle
machine to achieve a given cooling capacity, variable chiller
diverter valve 46 is set to direct hot gas exiting compressor 40 to
drive absorption chiller 24, see FIG. 1C. Specifically, variable
chiller diverter valve 46 diverts and regulates the amount of hot
gas exiting compressor 40 entering absorption chiller 24 required
to produce a desired degree of cooling. Absorption chiller 24 then
functions in the usual way, for example, for cooling the passenger
compartment of vehicle 10. Thus, gas-turbine 14 functioning as an
air-cycle machine both cools directly and also produces heat to
drive absorption chiller 24.
[0145] Vehicle 10 includes absorption chiller 24. In some
embodiments, a vehicle of the invention is devoid of an absorption
chiller and cooling is performed as described above with the
gas-turbine functioning as an air-cycle machine when in a passive
state. In some such embodiments, an air conditioner, such as 26, is
used together with the gas-turbine operating as an air-cycle
machine to provide sufficient cooling. In some such embodiments,
when the gas-turbine is an active state, cooling is provided using
an air conditioner such as 26.
[0146] Vehicle 10 includes air conditioner 26. In some embodiments,
a vehicle of the invention is devoid of an air conditioner as the
teachings of the inventions render such an air conditioner
superfluous. Instead, when the gas-turbine is in an active mode
cooling is provided by an absorption chiller and when the
gas-turbine is in an active mode cooling is provided by the
gas-turbine operating as an air-cycle machine, optionally in
combination with the absorption chiller.
[0147] In vehicle 10, shaft 42 of gas-turbine 14 is the rotor of
generator 16 allowing gas-turbine 14 to power generator 16
directly. In some embodiments, a generator is driven by a
gas-turbine in some other way. For example, in some embodiments, a
generator is driven by a power spool including a free turbine that
is rotated by energetic fluid such as exhaust gas produced by the
gas-turbine.
[0148] In vehicle 10, when gas-turbine 14 is in a passive state,
generator 16 functions as a motor to drive gas-turbine 14 to
operate as an air-cycle machine. In some embodiments, a vehicle is
provided with a dedicated motor, preferably an electric motor, to
drive a gas-turbine to operate as an air-cycle machine in the
passive state.
[0149] In vehicle 10, when gas-turbine 14 is in a passive state and
functions as an air-cycle machine, air-cycle machine intake valve
48 is set to allow ambient air to pass into turbine 38 without
entering rotary regenerator 34 (the primary heat-exchanger) or
combustor 36. In such a way, suction efficacy is improved and there
is a reduced chance that particles from ambient air will damage
components, especially the fine channels of rotary regenerator 34.
That said, in some embodiments, air passing into a turbine when the
gas-turbine is used as an air-cycle machine does not bypass a
combustor and/or a primary heat-exchanger.
[0150] In vehicle 10, gas-turbine 14 includes rotary regenerator 34
as a primary heat-exchanger to increase thermal efficiency by using
heat recovered from exhaust to preheat air entering combustor 36.
In some embodiments, a different type of primary heat-exchanger is
used instead of a rotary regenerator. In some embodiments, a
different type of primary heat-exchanger is used instead of a
regenerator, for example a recuperator. In some embodiments, a
gas-turbine does not recover heat from exhaust.
[0151] Vehicle 10 is an automobile where the teachings of the
invention are used primarily to cool the passenger compartment. In
some embodiments, a vehicle of the invention is another type of
vehicle. In some embodiments, a vehicle of the invention is a
commercial vehicle and the teachings of the invention are used to
cool a non-passenger cargo compartment, for example for the
transport of heat-sensitive cargo such as fish, meat or dairy
products.
[0152] In vehicle 10, gas-turbine operates according to an inverse
Brayton cycle both in the active and the passive state. In some
embodiments a vehicle is provided with a gas-turbine that operates
according to a Brayton cycle. In some embodiments, a vehicle is
provided with a gas-turbine configured to operate according to
either a Brayton cycle or an inverse Brayton cycle, for example as
described in U.S. Pat. No. 6,526,757.
[0153] A gas-turbine 64 operating according to a Brayton cycle for
implementing the teachings of the invention is depicted in FIG. 2A
in an active state for powering an electric generator 16 and in
FIG. 2B in a passive state when operating as an air-cycle machine.
In general, gas-turbine 64 is operated in the a manner analogous to
operation of gas-turbine 14 described above, with some differences
as detailed below.
Brayton Gas-Turbine in Active State for Generating Electric Power
(FIG. 2A)
[0154] Under certain driving conditions, for example in some
embodiments during high-speed cruising, gas-turbine 64 is operated
in an active state, burning fuel in combustor 36 to release energy
that is converted to mechanical energy by expansion through turbine
38, see FIG. 2A.
[0155] Air-cycle machine intake valve 48 is set to direct exhaust
gas exiting combustor 36 into turbine 38.
[0156] Compressor intake valve 68 is set so that compressor 40
draws ambient air through air intake 32.
[0157] Air-cycle machine heat-exchanger diverter valve 50 is set to
direct exhaust gas exiting turbine 38 to pass through the hot
stream section of rotary regenerator 34.
[0158] Compressor outlet valve 66 is set so that air exiting
compressor 40 is directed to the cold stream section of rotary
regenerator 34 and that exhaust exiting the hot stream section of
rotary regenerator 34 is directed to variable chiller diverter
valve 46.
[0159] Compressor 40 draws ambient air through air intake 32 and
forces the air through compressor outlet valve 66, through the cold
stream section of rotary regenerator 34 to be heated before
entering combustor 36. In combustor 36, the heated air is mixed
with fuel and the mixture combusted. The hot exhaust gas of the
combustion is directed into turbine 38.
[0160] The hot exhaust gas expands through and rotates turbine 38
(consequently rotating shaft 42 and compressor 40), passes through
air-cycle machine heat-exchanger diverter valve 50, through the hot
stream section of rotary regenerator 34, through compressor outlet
valve 66 and into variable chiller diverter valve 46. As discussed
above, variable chiller diverter valve 46 directs exhaust to be
ejected directly into the atmosphere as depicted in FIG. 2A, or to
drive absorption chiller 24.
Brayton Gas-Turbine as Air-Cycle Machine (FIG. 2B)
[0161] Under certain driving conditions, for example in some
embodiments during urban driving, in stop-and-go driving in a
traffic jam, gas-turbine 64 is operated in a passive state where
fuel is not combusted in combustor 36. When gas-turbine 14 is in a
passive state, electric power for powering drive motors 20 or
auxiliary loads is supplied by power-management unit 12, the
electric power drawn from power storage unit 18 or generated by
regenerative braking unit 30. When gas-turbine 14 is in a passive
state, gas-turbine 14 optionally functions as an air-cycle machine
to provide cooling for vehicle 10, see FIG. 2B.
[0162] Pump 60 of air-cycle machine heat-exchanger 22 is activated,
cycling fluid into fluid conduit inlet 56, through cooling fluid
conduit 22b of air-cycle machine heat-exchanger 22, out through
fluid conduit outlet 58, into passenger compartment cooling element
62 and back into pump 60.
[0163] Air-cycle machine intake valve 48 is set to direct air
entering air intake 32 into turbine 38 and to bypass combustor 36
and rotary regenerator 34.
[0164] Air-cycle machine heat-exchanger diverter valve 50 is set to
direct exhaust gas exiting turbine 38 to enter air-cycle machine
heat-exchanger 22 and to bypass rotary regenerator 34.
[0165] Compressor intake valve 68 is set so that air exiting gas
conduit outlet 54 of air-cycle machine heat-exchanger 22 is
directed into compressor 40.
[0166] Compressor outlet valve 66 is set to direct air exiting
compressor 40 to variable chiller diverter valve 46.
[0167] Generator 16 is set to function as a motor using power
supplied by power-management unit 12 from power storage unit 18
and/or regenerative braking unit 30 to rotate turbine 38 and
compressor 40 through shaft 42.
[0168] Compressor 40 draws air from the ducts leading to air-cycle
machine heat-exchanger 22, from gas conduit 22a of air-cycle
machine heat-exchanger 22, and from the ducts leading to turbine
38, generating low pressure in air-cycle machine heat-exchanger 22
and in the ducts leading to turbine 38. Ambient air enters air
intake 32, passes through air-cycle machine intake valve 48 and is
drawn through turbine 38. When exiting turbine 38, the air expands
and cools. The cool air passes through air-cycle machine
heat-exchanger diverter valve 50 to enter gas conduit 22a of
air-cycle machine heat-exchanger 22 through gas conduit inlet 52,
absorbs heat from cooling fluid in cooling fluid conduit 22b and
exits through gas conduit outlet 54 to pass through compressor
intake valve 68 to be drawn into compressor 40.
[0169] Cooling fluid in passenger compartment cooling element 62
absorbs heat from the passenger compartment of vehicle 10,
transfers the heat to the air in gas conduit 22a of air-cycle
machine heat-exchanger 22 and is therefore cooled.
[0170] The air draw into compressor 40 is compressed and
consequently heated, passes through compressor outlet valve 66 and
variable chiller diverter valve 46. As discussed above, variable
chiller diverter valve 46 directs exhaust to be ejected directly
into the atmosphere as depicted in FIG. 2A, or to drive absorption
chiller 24.
[0171] In the exemplary embodiments described above with reference
to the Figures, the teachings of the invention are implemented
primarily to cool the passenger compartment of a vehicle.
[0172] As understood from the above, in some embodiments, the
teachings of the invention are implemented, in some embodiments
additionally, to cool a non-passenger cargo compartment. For
example, in some embodiments, a vehicle is configured so that at
least part of the provided cooling provided is directed to a
non-passenger cargo compartment, for example, passenger compartment
cooling element 62 described above becomes cargo compartment
cooling element 62.
[0173] As understood from the above, in some embodiments, the
teachings of the invention are implemented, in some embodiments
additionally, to cool a power storage unit, such as a battery, of
the vehicle. For example, in some embodiments, a vehicle is
configured so that at least part of the cooling provided is
directed to a power storage unit, for example, passenger
compartment cooling element 62 described above becomes power
storage unit cooling element 62.
EXAMPLES
[0174] Reference is now made to the following examples, which
together with the above descriptions illustrate some embodiments of
the invention in a non limiting fashion. The calculations were
performed with the help of "GasTurb 11" by Dr. Joachim Kurzke
(Germany, www.gasturb.de) using representative values for a
gas-turbine operating according to an inverse Brayton cycle.
[0175] Cooling Using a Gas-Turbine as an Air-Cycle Machine
Input Conditions:
[0176] Air flow=0.06 kg/sec
Turbine expansion ratio=1.55
Compressor pressure ratio=1.566
Ambient Temperature=30.degree. C.
Ambient Pressure=101.35 kPa
Ambient humidity=60%
Turbine efficiency=85%
Compressor efficiency=77%
Heat-exchanger efficiency=90%
Heat-capacity factor of air (C.sub.p)=1.005 kj/(kg K)
Calculated Performance:
[0177] Enthalpy drop of turbine=30.5 kJ/kg
Enthalpy rise of compressor=53.5 kJ/kg
Turbine outlet temperature=0.degree. C.
Turbine outlet pressure=64.7 kPa
Air-cycle machine heat-exchanger outlet temperature=3.degree.
C.
Air-cycle machine heat-exchanger inlet temperature=30.degree.
C.
Compressor outlet temperature=80.3.degree. C.
Compressor outlet pressure=102 kPa
Compressor inlet temperature=27.degree. C.
Compressor inlet pressure=62.7 kPa
Motor power requirement=0.050 kW [0178] (based on a hot pressure
drop of 1 kPa, an air flow of 0.06 kg/sec and Motor electric
efficiency of 80%)
[0178] Alternator electric efficiency=0.95
electric power requirement (cooling+motor
power)=(53.5-30.5)*0.06/0.95=1.45 kW+0.05 kW=1.5 kW
Cooling Capacity=1.005*(30-3)*0.06=1.63 kW
Coefficient of Performance ( COP ) = cooling capacity / power
requirement = 1.63 / 1.5 = 1.09 ##EQU00001##
[0179] Cooling Using a Typical Gas-Turbine as an Air-Cycle Machine
Together with an Absorption Chiller
Input Conditions:
[0180] Temperature of the cooled absorption chiller
generator=24.degree. C.
Compressor inlet temperature=80.3.degree. C.
Absorption chiller heat-exchanger efficiency=90%
Calculated Performance:
[0181] Cooling capacity of absorption
chiller=(80.3-24)*0.06*0.9=3.04 kW
Combined cooling capacity (chiller+air-cycle machine)=3.04 kW+1.63
kW=4.67 kW
Coefficient of Performance ( COP ) = cooling capacity / power
requirement = 4.67 / 1.5 = 3.11 ##EQU00002##
[0182] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
[0183] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the scope of the appended claims.
[0184] Citation or identification of any reference in this
application shall not be construed as an admission that such
reference is available as prior art to the invention.
[0185] Section headings are used herein to ease understanding of
the specification and should not be construed as necessarily
limiting.
* * * * *
References